Characterization of Mi_1.2 Whitefly (Bemisia tabaci) Resistance Gene

Abstract

Tomato (Solanum peruvianum) Mi gene provides resistance to whitefly (Bemisia tabaci), potato aphids and nematode making Mi a useful source in integrated pest management program. The aim of this work was to isolate, clone and sequence Mi_1.2 gene from S. peruvianum. In addition, physico-chemical identification of amino acids deduced from Mi_1.2 gene was done. Secondary (2D) and tertiary (3D) structures of Mi_1,2 protein were also predicated. Distinct amplicons of 620, 600, 3300 and 1993 bp were successfully amplified using PCR amplification. The full-length DNA (5.4 kbp) and cDNA (4 kbp) of Mi_1.2 gene was isolated using specific primers. Fragments 620 and 600 bp cloned into Escherichia coli XL-1 Blue and sequenced. Sequencing results of both assembled fragments (620 and  600 bp) joined at the overlap region (1440 bp). A BLAST search confirmed  that the DNA sequence from the amplified fragments was Mi_1.2 gene. It shared 98% identity and deduced amino acids shared 97% identity with Mi_1.2 gene published in GenBank. An Open reading frame (ORF) of Mi_1,2 protein encoded for 479 amino acid residues with molecular weight 54.59 KDa and  isoelectric point (PI) 5.52 was calculated using Expasy’s ProtParam server. 2D and 3D structures of Mi_1.2 protein was analyzed using SOPMA and Swiss-Prot software, respectively.